Make changes to our blog layout (WordPress) – excerpts

We have a blog here – https://www.zeronews-fr.com/

This section is where we want to make changes – https://prnt.sc/vn9bve

We want to do 2 things here.

1) Make the excerpt longer (100 words) and also include all html/tags
2) Make the blog section load all posts and show a “see more” button that displays the ‘hidden’ posts

Alternatively, we’d like a section where the blog posts can scroll to the right (4/6 at a time) And have unlimited scrolling.

it’s imperative that the blog load ALL content when the site loads, and renders it fully, but hide the content behind the “see more” button or scrolled to the right.

Thanks!